(a) Technical Field
The present invention relates to a system and method for calculating distance to empty (DTE) of a green vehicle. More particularly, the present invention relates to a system and method for calculating a DTE of a green vehicle, which can compute available energy of a battery and more accurately compute DTE using the computed available energy.
(b) Background Art
Green vehicles are considered as any green vehicle which does not discharge exhaust gas. These types of vehicles include a pure electric vehicle driven using power of an electric motor, a hybrid vehicle driving using combined power from a motor and an engine, a fuel cell vehicle driven via power from an electric motor operated by electricity generated within a fuel cell, or any other vehicle that has substantially lower emissions that a conventional internal combustion vehicle.
A high-voltage battery as an electric power source for driving a motor, a converter, etc., are often mounted in such a green vehicle. The current status of the battery should be maintained at a satisfactory level by monitoring the voltage, current, temperature, etc. of the battery and estimating a temperature of the battery and a degree of degradation of the battery including a state of charge (SOC) [%] of the battery. Therefore, a battery management system (BMS), e.g., a kind of controller, is mounted in the green vehicle, to generally manage various states of the battery, preventing reduction in lifespan of the battery due to the degradation of durability of the battery, estimating the SOC of the battery, and the like.
As such, it is very important to detect the SOC of the battery in the green vehicle using the high-voltage battery. Particularly, it is required to develop a technique for informing a driver of distance to empty (DTE) through the medium of a cluster by detecting the SOC of the battery, etc., while driving.
Generally, in gasoline and diesel vehicles, a system and method is applied in which a current DTE is predicted in such a manner that measures the amount of fuel in a fuel tank using a sensor, etc. and multiplies accumulated fuel efficiency by the amount of remaining fuel. However, in green vehicles, the current DTE is predicted by measuring the amount of discharge current used per unit of time (e.g., a second or minute) in a battery and accordingly estimates a current SOC of the battery.
Hereinafter, a conventional method for DTE computation of a green vehicle will be described with reference FIGS. 1 and 2. First, a current SOC of a battery is estimated by an SOC computation unit 10 within a controller.
Estimating the current SOC of the battery is performed by measuring the amount of discharging current used per unit of time in the battery and accumulating the measured amounts and then correcting the SOC by adding/subtracting data on disturbance elements (e.g., temperature and degradation of the battery) data and an open circuit voltage (OCV) for voltage compensation of the battery to/from current accumulated data.
Next, a current DTE is computed based on an SOC estimated in a DTE computation unit 40. In this case, the estimated SOC and the computed DTE are stored in a memory 60. Thus, the current DTE is finally computed in such a manner that adds/subtracts an initial value of DTE according to a learning logic to/from the DTE computed based on the estimated SOC. Then, the finally computed current DTE is displayed in a cluster display 50 so that a driver can identify the current DTE.
When a driver starts the vehicle in an indoor parking state and drives the vehicle outdoors or parks the vehicle outdoors, external temperature is lowered. However, as the temperature of the battery among disturbance elements is not considered in the computation of the DTE, the temperature of the battery is also lowered. Therefore, the DTE is not accurately computed but computed rather excessively (i.e., high). Further, the DTE is rapidly reduced in a low SOC of the battery during long-distance driving.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.